1. Field of the Invention
The present invention relates to methods for preventing soil expansion from affecting the structure of a building. More particularly, the present invention relates to in-situ void systems that are used to accommodate soil expansion in areas adjacent to the foundation of a structure.
2. Description of Related Art
There are several methods commonly utilized prior to construction to prevent highly expansive soils from damaging structures that are either supported or contained within the earth. These methods can be divided into void systems and soil treatments. The void systems utilize forms to create a void beneath or adjacent to a structure so as to allow for expansion of soils without damage to the structure. The soil treatment includes either water or chemical treatments prior to construction for the purpose of reducing the potential of the soil to expand and damage the structure.
Although these methods are useful, they have certain disadvantages. The void systems can be divided into cardboard void forms and low density EPS void forms. These two are the most commonly accepted methods for reducing the potentially damaging effects of expanding soils. However, due to their high cost, they are typically only used at perimeter locations, rather than throughout the full foundation area. Also, the cardboard forms have the added disadvantage of serving as a reservoir for water to sit adjacent to areas not having voids. As such, this will create a situation whereby the adjacent area is damaged due to expanding soil. Likewise, the EPS void systems have the added disadvantage of not being fully compressible and thereby not alleviating as much expansion as might be necessary to avoid damage. The EPS void system is otherwise known as a STYROFOAM (TM) void form.
The water and chemical treatments are also costly and have the added disadvantage of being difficult to verify proper application. These systems are subject to significant operator error during the treatment. As a result, a customer may pay for the treatment and effectively gain no significant reduction in the potential for damage from the soils that were so treated. Additionally, the various types of nozzles employed for such water and chemical treatments often become clogged or damaged when placed into the earth. The soil in the proximity of the nozzle will often clog the nozzle so that the proper amounts of water and chemicals are not delivered from the nozzle. Methods for conditioning soil after construction, in order to minimize or reduce damage from expanding soils, are not available in the current art.
It is an object of the present invention to provide a void system which minimizes soil expansion.
It is another object of the present invention to provide a void system which minimizes structural damage to a building or a foundation.
It is still another object of the present invention to provide a void system which effectively absorbs any expansion of the soil.
It is a further object of the present invention to provide a void system which reduces soil expansion potential against the walls of the structure.
It is a further object of the present invention to provide a void system that can be applied to either existing structures or prior to the formation of the structure.
It is still another object of the present invention to provide a void system that effectively maintains the structural integrity of foundations and basements.
It is still another object of the present invention to provide a void system which is easy to use, relatively inexpensive and easy to implement.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.
The present invention is a method of forming an in-situ void system comprising the steps of: (1) determining an expansion potential of the soil adjacent to a structure; and (2) forming an array of voids in an area adjacent to the structure so as to accommodate the expansion potential of the soil. The step of forming the array of voids can be carried out by drilling an array of holes beneath the structure. This array of holes can be drilled to a depth of the soil potential. Alternatively, the array of holes can be drilled around a perimeter of the structure.
In the present invention, a liquid can be introduced into the array of voids so as to swell the soil. The liquid can be either water or a mixture of water and lime. When lime is used, the lime will react with the minerals within the clay so as to stabilize the clay in the soil.
In the present invention, the structure can be the foundation of the building. When the structure is the foundation of the building, the method of the present invention also includes laying the foundation over the array of voids subsequent to the step of forming the array of voids. The top of the array of voids is covered with a material prior to laying the foundation. This material can either be a rigid plastic sheet having a structural integrity suitable for withstanding the weight of the foundation or it can be a fill soil interposed between the top of the array of voids and the bottom of the foundation.
When the structure of the present invention is an existing structure, the step of forming the array of voids can include drilling an array of holes around a perimeter of the existing structure to a depth at least as deep as the existing structure within the soil.
Within the concept of the present invention, the holes can be drilled vertically or horizontally. The array can be either geometrically regular or geometrically irregular. The array of voids can be a grid of trenches formed in a soil matrix. These trenches can be either vertical, horizontal or any orientation therebetween.